Closed die molding a detergent bar



June 1961 0. LUNDBERG ETAL 2,987,484

CLOSED DIE MOLDING A DETERGENT BAR Filed May 29, 1959 m m m j w z M C xm J a x a a o). a r. m2 x e m E: im v 1h m J A M I: a 6

ATTORNEYS.

United States Patent 2,987,484 CLOSED DIE MOLDING A DETERGENT BAR OlleI. Lundherg and Joseph Blinks, Springfield Township, Hamilton County,Ohio, assignors to The Procter & Gamble Company, Cincinnati, Ohio, acorporation of Ohio Filed May 29, 1959, Ser. No. 816,778 16 Claims. (Cl.252-474) This invention relates to a process for closed die molding asubstantially non-soap synthetic detergent composition in the form of atoilet bar having outstanding characteristics.

It is an object of this invention to provide a fluid mixture ofsynthetic detergent and a binder vehicle which can be closed die moldedand solidified and which re sults in a detergent bar having desirableproperties of milled toilet bars while being free from undesirableproperties of milled toilet bars.

Another object is to provide a closed die molding process for makingsynthetic detergent bars which utilizes a fluid, detergent-containingmixture capable of rapidly forming a strong shape retaining shell in asubstantially closed precooled mold whereby a comparatively short molddwell time permits rapid production of such bars.

Another object is to provide a process for making a synthetic detergentbar in which air or other gases are dispersed in the fluid detergentcomposition thereby resulting in a bar which will float in water.

A further object is to provide a process for making synthetic detergentbars free from cleavage planes and orientation of structure.

Another object is to provide means for solidifying a synthetic detergentcomposition in a phase condition corresponding to that achieved byworking or milling.

A still further object is to provide a closed die molding process formaking synthetic detergent bars which process overcomes disadvantagesinherent in conventional milling processes.

The description of the process employed and the detergent bar producedby the process, which is hereinafter more fully set forth, will be moreclearly understood when taken in conjunction with the drawing whichshows a flow diagram in FIGURE 1, an example of a suitable mold for thebar in FIGURE 2, and a cut-away view of a finished closed die molded barin FIGURE 3.

The present invention is based on the discovery that if a detergentcomposition containing a normally solid synthetic detergent (classifiedherein as non-soap") and a proper binder-vehicle can be injected into asubstantially closed precooled bar mold, while in a fluid condition(having the proper viscosity characteristics as hereinafter described),the ultimately solidified detergent bar will be in a crystalline phasecondition corresponding to that of a bar of the same composition whichhas been worked in a plastic state, providing the fluid composition iscooled in the mold from a nigre or nigreplus-crystals phase.

Hitherto in the industry it was understood that bars could be formedeither by framing or by a process, such as milling, involving workingthe composition in a plastic state. Framing methods, in which neat soapor synthetic detergent stock is semi-fluid, produce bars which aregenerally weaker and softer than milled bars, are limited to arectangular shape and do not have the smooth shiny surfacecharacteristic of milled bars. Moreover, framed or cast bars are slowlyand unevenly cooled and tend to have oriented structure, cleavage planesand segregation of ingredients. Machines and methods for the continuousframing or casting of soap bars have been proposed but have notexperienced widespread use apparently because they have not overcome thebasic disadvantages of .framed bars and processes for making them.Framing, to all intents and purposes, is no longer used for themanufacture of toilet bars.

Processes for making toilet detergent bars which involve working thedetergent-containing material in the plastic state include the wellknown milling process on one hand and the freezer process described inUS. Patent 2,295,594 to Mills on the other. But it has always beenunderstood that a process of working a soap composition in a plasticcondition was necessary to secure a desirable crystalline condition, adesirable texture, and a desirable solubility in a toilet bar. Barmaking procedures involving working in a plastic consistency (which arenecessary in the case of a soap composition) have always hitherto beenconsidered by the art to be necessary in the case of a syntheticdetergent composition. The synthetic detergent bars which haveheretofore met with a significant degree of commercial success are madeby conventional soap milling processes using binders and plasticizerswhich impart sufiicient plasticity to the synthetic detergent and resultin suitable finished bar characteristics.

Substantially non-soap synthetic detergent bars have long been desirablebecause of their ability to resist precipitation and the formation ofcurds by inorganic salts imparting hardness to water. Commonly marketedsoap bars are subject to this undesirable precipitation and curdformation.

The synthetic detergents which are normally solid at room temperatureand which are useful for bar formulation do not readily bind themselveswith water and do not readily soften with heat or moisture sufiicientlyto enable formation into bars in the manner that soap and water areformed into a workable plastic mass for processing into strong usablebars. Moreover, bars made only of synthetic detergents tend to absorbmoisture more rapidly than soap bars, thus shortening their useful lifeand making them smeary and unattractive in appearance during use. Beforesynthetic detergents can be used in a practical bar form, they must becombined with a compatible binding agent that gives the bar strength andthat reduces the penetration of moisture into the bar. A suitablebinding agent should not impart undesirable characteristics to the baror adversely affect detergency and lathering.

Consequently, while the art has suggested for synthetic detergentcompositions bar producing methods which are etfective with soapcompositions, particularly milling, it has not hitherto been known thatany bar product could be made (having the texture and othercharacteristics of a milled soap or detergent bar) from a composition ofsynthetic detergent and a binder-vehicle, excepting by a procedureinvolving working the composition in plastic state.

The discovery that a synthetic detergent bar could be produced havingthe texture, solubility, and other initial appearance and performancecharacteristics of a milled product formed of the same material,providing the composition is cooled from or through a nigre ornigre-pluscrystals phase condition, makes possible the attainment notonly of those advantages hitherto secured in milled products, but alsoof other advantages which hitherto could not be secured at all. Also anumber of the disadvantagw of milled products are avoided.

The desirable properties of milled detergent bars include strength,hardness, firmness, smoothness, shiny surface and rounded shape (fromstamping). However, milled bars can be made in only a limited number ofshapes because they must be cut and stamped in a relatively firm form.Moreover, milled bars, because the material from which they are made isplodded, extruded and stamped, have an oriented structure (ordered,aligned, or arranged along the axis of extrusion) and a tendency to havecleavage planes in the bar. Cleavage planes tend to cause weaknesswithin the bar and because of alternate wetting and drying, tend toresult in the wet-cracking of the bar along the planes during washstanduse. Wet cracks are undesirable because they are conducive to fracturingof the bar, and often the open cracks become filled with dirt, leadingto an unsightly bar.

The freezer process, in which floating soap bars can be made, alsoinvolves extrusion and the tendency to have oriented structure andcleavage planes in the bar. Floating bars are desirable and many methodshave been proposed to make floating milled bars but none has met withany commercial success.

The closed die molding process of the present invention makes itpossible to avoid the disadvantages of milled bars, to obtain theadvantages of milled bars and to obtain advantages hitherto unobtainablein other bar making processes. Bars of any shape, with or withoutimprinted wording or designs thereon, can be easily and rapidly made andsuch bars will be firm and have a smooth shiny surface like milled bars.Bars which will float in water can be formed by injecting anappropriately aerated fluid detergent composition. Multi-colored barscan be made by injection of more than one differently colored detergentmixture. Closed die molding results in the cooling and solidification ofa fluid detergent composition in a static state resulting in a bar freefrom the oriented structure and cleavage planes formed in bar makingprocesses which involve plastic working.

The closed die molding processes of this invention involves the rapidinjection through a comparatively small orifice, of a basically non-soapfluid mixture of synthetic detergent and a binder-vehicle, capable ofrapid solidification to a shape sustaining form, into a substantiallyclosed precooled mold. After solidification to at least ashape-sustaining form, the bar is ejected from the mold for furthercooling as necessary. The resulting bar has outstanding characteristicsand does not form hard water curds. Air or other gases can be optionallydispersed intimately in the fluid mixture, especially if a bar capableof floating in water is desired. The dispersed gas forms confined voidson cooling.

The main problems encountered in successfully making detergent bars byclosed die molding were the provision of a suitable mixture of syntheticdetergent and vehicle and suitable conditions for the process. Such asuitable mixture must be fluid, capable of rapid solidification attemperature within practical ranges and capable of forming a shapesustaining shell without necessarily com plete solidification in orderto permit commercially feasible production rates. Such fluid mixtureshave not been used in the art. Mixtures of synthetic detergent, waterand various binders used to make milled bars are heavy plastic massesduring milling. Means are not known in the art for making such mixturesfluid enough for closed die molding without damaging them by the use ofhigh temperature, without formulating the mixtures so that a usefuldetergent toilet bar is not obtained or without introducingdifficulties, such as undesirable shrinkage or foaming, into the barmolding process.

The surprising observations that are made are that by proper choice ofingredients, processed as hereinafter described, a bar havingoutstanding characteristics is obtained without milling or working andthat the solidified bar has crystalline characteristics (as determinedby X-ray diffraction analysis) which are substantially the same as thecrystal characteristics of a bar made of substantially the sameingredients milled or worked in a plastic condition by conventionalprocesses. It is well known that solid hydrated soap can be obtained inat least three different crystalline forms having different tillphysical and performance characteristics and that the form obtained isdependent on the method by which the soap is processed. For example,framed soap is usually predominantly in the omega phase and can, betransformed into the beta phase (having markedly different and superiorcharacteristics) by milling or mechanical working.

In connection with the study of the phase (temperature-composition)behavior of the molten dispersions of synthetic detergent in the fattyvehicle which are closed die molded in accordance with the presentinvention, it was discovered that the dispersion must be cooled throughthe nigre (isotropic liquid) plus crystals phase. Preferably it iscooled from this phase condition as well as through it although it canbe cooled from the nigre phase and then through the nigre plus crystalsphase if excessive temperatures as hereinafter described are avoided.Mixtures of vehicle and synthetic detergents in the neat or middle(anisotropic liquid) phase are not suitable for closed die moldingbecause of the excessive viscosity of those phases and the tendency forundesirable complexcs to form in those phases.

It is surprising that successful closed die molding requires cooling themolten dispersion through the nigre plus crystals phase and theavoidance of neat and middle phases since there is nothing in the art ofsoap bar manufacture which would give such an indication. Neat soap,while more fluid than other soap phases used in soap bar manufacture, isa heavy viscous fluid. Neat soap is used in the framing method formaking bars. The freezer process utilizes a predominantly neat pluscrystals phase which is a heavy plastic mass. The even heavier plasticmass used in making milled soap bars is in a nigre plus crystals phase(with some neat soap), and is unsuitable for use in the framing method.Thus, the closed die molding process of this invention utilizes adetergent-containing mass having a physical condition and phaserelationship foreign to conventional soap bar making processes. Closeddie molding produces bars having desirable properties characteristic ofmilled bars but, because the detergent-containing mass is notmechanically worked as is done in milling, the closed die molded bar hasadditional valuable propcrties not found in milled bars.

Synthetic detergents The non-soap synthetic detergents found to beuseful in this invention may be broadly designated as the anionic,normally solid, water soluble salts of organic sulfuric reactionproducts having in their molecular structure an alkyl or acyl radical ofcarbon atom content within the range of about 10 to about 18 carbonatoms and a sulfonic acid or sulfuric acid ester radical. These salts,more specifically hereinafter defined, were found to possess theproperties required for eflicient execution of the closed die moldingprocess of this invention and also for obtaining outstandingcharacteristics in the finished bar. These normally solid salts arereadily dispersable in the molten vehicle. They remain uniformlydispersed in the melt upon injection and cooling. They result in firm,strong smooth bars which lather and clean well. In use, the bars do notbecome unduly slimy, waste away, or crumble and do not form wet crackswhich collect dirt.

It was observed that only the normally solid anionic non-soap sulfateand sulfonate detergents herein defined form satisfactory bars. Anionicdetergents which are normally liquid or pasty in form result in barswhich are undesirably soft, weak and slimy in use.

Important examples of normally solid synthetic detergents which form apart of the outstandingly useful compositions of this invention includesodium and potassium alkyl glyceryl ether sulfonates, especially thoseothers of higher fatty alcohols derived by the reduction of coconut oil;the reaction product of higher fatty acids with sodium or potassiumisethionate, where, for example, the fatty acids are derived fromcoconut oil; sodium or potassium salts of a higher fatty acid amide of amethyl taurine in which the higher fatty acyl radicals, for example, arederived from coconut oil; sodium or potassium alkyl benzene sulfonatesin which the alkyl group contains from about 9 to about carbon atoms ineither a straight chain or preferably a branched chain which is derivedfrom polymers of propylene; dialkyl esters of sodium or potassium saltsof sulfosuccinic acid, for example the dihexyl ester; sodium andpotassium alkyl sulfonates and sulfates, especially those alkyl sulfatesderived by sulfation of higher fatty alcohols produced by reduction ofoils of the coconut oil group, such as coconut and palm kernel oils;sodium and potassium salts of sulfated or sulfonated monoglyceridesderived, for example, from coconut oil; sodium or potassium salts of thehigher fatty alcohol esters or sulfocarboxylic acids, for example, thesodium salt of the lauryl alcohol ester of sulfoacetic acid; and othersknown in the art a number being specifically set forth in U.S. PatentNo. 2,486,921 issued to Byerly on November 1, 1949.

The above list of normally solid non-soap detergents is given only forthe purpose of illustrating the types of detergent compounds useful inthe practice of this invention and it will be appreciated that the scopeof the invention is not thereby limited.

As those versed in the art well know,- certain of the normally solid,anionic, non-soap detergents and their homologues have more desirablesolubility, latherability, hygroscopicity and mildness characteristicsthan others and the detergents selected for use can depend on theparticular characteristics to be emphasized. The preferred syntheticdetergents for the process and product of this invention are the watersoluble, alkyl glyceryl ether sulfonates, acyl isethionates and N-methylN-acyl taurides in which at least 50% of the alkyl and acyl radicalscontain 12 carbon atoms in a straight saturated chain.

Vehicle The binder vehicle material used in the practice of thisinvention should be one that forms with the synthetic detergent a fluidmolten dispersion which upon cooling through the nigre plus crystalsphase, forms a bar of outstanding physical and performancecharacteristics. It was found that to fulfill these requirements thevehicle should have certain properties as hereinafter described.

First, the vehicle should be a normally solid, organic material having amelting point in the range of about 120 F. to about 220 F., preferablyabout 130' F. to about 190 F. These ranges are above the usual maximumsummer temperature that the bar must resist. Vehicles which melt aboveabout 220 F. are undesirable because of high heat requirements in theprocess. Moreover, the vehicle should have a comparatively sharp meltingpoint and must be capable of changing from a fluid state to a relativelystrong crystalline solid within a temperature drop which will befeasible in view of the permissible cooling time within the mold. Thevehicle material must have a comparatively sharp melting point withinthe above melting point range even when it is modified by the dispersionin it of the detergent component or other additives as hereinafterdescribed. Soap, which is used as a binder in some commercial detergentbars, is unsatisfactory as the vehicle in the process of this in ventionsince it is too viscous and melts and solidifies comparatively slowlyover a rather broad temperature range; but minor amounts of soap may bebeneficial as hereinafter described.

Second, the vehicle, in its normally solid form in the finished bar,should have low solubility in water but have an aflinity for water sothat the behavior of the solidified dispersion of synthetic detergentand vehicle is comparable, in washstand use, with the conventional fattyacid soap toilet bars such as those made from the sodium salts of fattyacids derived from a fat and oil mixture containing about 75% tallow andabout 25% coconut oil. The vehicle should have some aflinity for waterin order to obtain desirable lathering characteristics in the bar.However, if a vehicle material is so soluble in water that it results ina bar which dissolves quickly, wastes away or becomes unduly soft orslimy in washstand use, it is unsuitable for a vehicle. On the otherhand, if a material has such a low affinity for water that it results ina bar which does not release the synthetic detergent material duringrubbing for detergency in the form of lather, it is unsuitable for avehicle. Moreover, a material which has too low aflinity for waterresults in a bar with a grittydraggy feeling to the hands making itundesirable for personal use.

The materials which were found to be useful as the vehicles in theprocess and products of this invention and which have low solubility inwater, an aliinity for water, and comparatively sharp melting pointswithin the abovementioned ranges, include saturated higher molecularweight fatty acids, saturated higher molecular weight fatty alcohols,and monoand di-esters of gylcerol, ethylene glycol or di-ethylene glycoland saturated higher molecular weight fatty acids. Strong, firm, smoothsurfaced bars can be produced using these vehicles. It was found thatonly the saturated fatty acids and their abovementioned derivatives canbe used since they are normally solid; have comparatively sharp meltingpoints above about F. and are substantially resistant to oxidation.Because of the heating in the process, appreciable amounts ofunsaturated fatty acids, and their derivatives, being oxidizable, areundesirable although small amounts can be tolerated, especially thosewith only one double bond. Odors of oxidized fatty acids may interferewith desired perfuming. The fatty vehicles found to be most useful inthe practice of this invention are those with carbon atom chains in thefatty radical ranging in length from about 16 to about 22, preferably 16to 18. However, any of the above mentioned fatty vehicles, or a mixturethereof, with a melting point in the range of about 120 F. to about 220F. is useful.

Examples of the useful fatty vehicles include palmitic acid, stearicacid, arachidic acid, behenic acid, the monoand di-esters of glycerol,ethylene glycol or diethylene glycol and such fatty acids, cetylalcohol, stearyl alcohol, arachidyl alcohl and behenyl alcohl. Minoramounts (not substantially in excess of about 5%) of saturated fattyvehicles with carbon atom chains of 14 or 24 such as myristic acid,lignoceric acid, the monoand di-esters of glycerol, ethylene glycol ordiethylene glycol and such fatty acids, myristyl alcohol and lignocerylalcohol, can be tolerated in the melt and finished bar and even can bebeneficial. Other normally solid materials having a low solubility inwater and an affinity for water similar to these fatty vehicles andhaving a melting point in the range of about 120 F. to about 220 F. canbe used. Fatty acids are preferred vehicles.

The fatty materials used for the vehicles of this invention have theability to permit incorporation of a gas, such as air or nitrogen,intimately dispersed in the melt used in the closed die molding processof this invention. It is desirable to be able to incorporate gas in amaterial used to make detergent bars because it is an economical methodof increasing the volume of the bar, and it can result in a bar ofreduced specific gravity capable of floating in water.

Normally solid petroleum derivatives with melting points within therange of about 120 F. to about 220 F. such as paraffin are notsatisfactory vehicle materials because they do not have an afiinity forwater. Petroleum derivatives, even when associated with a large amountof synthetic detergent, severely inhibit the lathering and detergencyproperties of the bar. They are difficult to disperse in water, oftenproduce a greasy scum in the water and impart a poor texture to the bar.Very minor amounts could be tolerated, however.

Proportions of vehicle and synthetic detergent The molten mixtures usedin the process of this invention contain by weight an amount of vehicle,an amount of synthetic detergent and, if desired, amounts of vehiclemodifiers and/or additives, as hereinafter described. In the followingdiscussion of proportions of vehicle and synthetic detergent, it is tobe understood that combinations which do not total 100%, include suchmodifiers and/or additives to total 100%. Moreover, the proportions ofingredients in the molten mixture are substantially the same as those inthe resulting finished bar.

Even though the materials used as vehicles in producing the bars of thisinvention are only sparingly soluble in water, they readily disperse inwater upon rubbing and lathering of the bar because of their favorableaffinity for water and their close association in the bar with thesynthetic detergent.

Vehicle materials constitute from about 22% to about 50%, preferablyabout 24% to about 35%, by weight of the molten mixture used in theprocess of this invention. Up to about 50% the amount of vehicle presentin the melt results in a tolerable performance load in the finished bar.When up to about 50% vehicle is present in the finished bar. the amountof synthetic detergent used to cause dispersion of the vehicle in waterdoes not unduly affect the lathering and detergency of the bar. However,if the amount of vehicle in the finished bar exceeds about 50%. theexcess vehicle acts as a more pronounced performance load in that itunduly inhibits the lathering properties and solubility of the bar.

At least about 22% of the melt used in closed die molding the detergentbars of this invention should constitute vehicle. It has been found thata melt containing less than about 22% vehicle cannot be madesutficiently fluid, at the temperature desired, to be properly utilizedin the process of this invention. The properties and requirements ofmelt fluidity are hereinafter more fully described.

The molten mixtures used in the process of this invention contain fromabout 35% to about 7%, preferably about 40% to about 60%, by weight ofsynthetic detergent. Amounts of detergent less than about 35% of thefinished bar do not result in a bar with satisfactory luthcring ordetergency properties. Amounts of synthetic detergent greater than about70% are unnecessary to produce a toilet bar of outstanding lathering anddetergent characteristics.

It has been found that. within these percentage ranges of syntheticdetergent and vehicle, greater proportions of synthetic detergent tovehicle result in bars which will lather better than those with greaterproportions of vehicle. It has also been found that, within theseranges. greater amounts of vehicle result in more favorable closed diemolding characteristics. The preferred ratio range of syntheticdetergent to vehicle is about 2.511 to about 1.2:l.

The term normally-solid when used in connection with the description ofthis invention means a substantially solid crystalline form at ordinaryatmospheric tem peratures and pressures. the temperatures being thoseranging up to about 110 F.

Formation of molten dispersion To form the melt used in the moldingprocess of this invention, the synthetic detergent and the vehicle canbe melted together and agitated or the detergent can be dispersed withagitation in molten vehicle. The melt is formed in a fluid injectablestate. This state requires that the synthetic detergent be substantiallyuniformly dispersed in the liquid vehicle and that the viscosity of themelt be within a range of from about 2,000 to about 50,000 centipoisesat the conditions of injection. Viscosity of the melt is dependent onthe intensity of shearing force agitation and on temperature; it is afunction of the composition and phase of the melt. Continuous agitationof the melts used in the injection process is essential for maintaininguniform dispersion of the melt components and a viscosity within theaforementioned range.

A viscosity within the above range is obtainable when the temperatureand composition of the melt are such that the melt will cool through thenigre plus crystals phase. The melt can be in the nigre plus crystalsphase when it is injected or it can be in the nigre phase when it isinjected if excessive temperatures as hereinafter described are avoided.if the melt is initially in the nigre phase, it will always cool throughthe nigre plus crystals phase: however, the melt is preferably initiallyin the nigre plus crystals phase since lower melt temperatures arepreferred as hereinafter described.

The viscosity of the melts can be measured in two ways. A viscometer,such as the Brookfield viscometer, placed in the melt will give areading directly in centipoises. The Brookfield Viscometer is aconcentric cylinder rotational type of viscometer the principle of whichis described in volume 8 of the Journal of the Society of CosmeticChemists, pp. 282300 (1957) along with other types of viscometers whichcould be used.

Viscosity can also be measured using the Hagen Poiseuille equation whichis based on the measurement of pressure drop of a liquid flowing in atube. This equation is discussed in Elements of Chemical Engineering" byBadger and McCabe (1936) on page 33. The equation gives viscosity inEnglish units (pounds per foot second); this can be converted tocentipoises since one English unit equals 1.488 centipoises.

The melts used in the process of this invention exhibit a thixotropicbehavior which results in a high apparent viscosity at low rates ofshear and a decreasing viscosity at increased rates of shear. Theviscosity of the melts varies with changes in the types and proportionsof detergent and vehicle in the melt and with the phase of the melt.

A melt having a viscosity in the range of about 2,000 to about 50,000centipoises at injection conditions is thick enough so that it will notundesirably splash in the mold. eutrap air or run out of the mold airvents and is thin enough to permit complete filling of the mold prior tosolidification of any composition therein which would have to bedisplaced during a continuation of the filling and thin enough to avoidexcessive injection pressures.

Substantially uniform dispersion is necessary to obtain. from the closeddie molding processes of this invention, a homogeneous bar which isfirm, strong and smooth. Uniform dispersion results in uniform wearingof the bar ingredients when the bar is lathered. The uniform dispersionof the dissimilar ingredients of the bar composition of this inventionprovides its good physical characteristics. Materials used as thevehicle component are usually brittle alone and the synthetic detergentsused are usually noncohesive alone. However, when uniformly combined inthe above mentioned ranges, these components result in a strong, firm,smooth bar which will not become unduly slimy in use and which is in acrystalline phase condition corresponding to that found in milledsynthetic detergent bars.

As used herein in connection with the molten mixtures of syntheticdetergent and vehicle, the terms dispersion" and "disperse" are intendedto include solution and dissolve. The synthetic detergent is at least inpart soluble in the molten fatty vehicle. Dissolved detergent will be inthe nigre portion, and the undissolved detergent will be in the crystalsportion, of the nigre plus crystals phase. However, solubility of thedetergent in the molten vehicle varies with the type of detergent andthe temperatures of the melt. Solubility increases with highertemperatures toward complete solution in the nigre phase.

Whether the synthetic detergent is uniformly dispersed in the melt inthe form of a solution, in the form of crystals or somewhere in between,the processing characteristics are not noticeably atfected as long asother processing conditions as described herein are observed.

It has been found that the proper viscosity for a fluid injectable statecan be obtained by maintaining the melt at a temperature in the range ofabout 160 F. to about 300 F. depending on the melting point of the melt.Preferred temperatures are found in the range of about 180 F. to about250 F. Lower temperatures in these ranges are usually desirable toreduce the heat requirements in the process and to reduce the amount ofcooling required to solidify the bar provided the melting point of themelt permits such a temperature lowering. If temperatures higher thanabout 300 F. are used, there is danger of the ingredients of the meltdiscoloring, forming odors or decomposing. Moreover, high temperaturesalso encourage the formation of undesirable complexes and other chemicalcombinations of the components. Such complexes and combinations tend tomake the melt more viscous and result in a soft bar having inferiorlathering properties.

The temperature in these ranges at which any given molten dispersion ofvehicle and synthetic detergent is in a fluid injectable state dependson the types and proportions of vehicle and detergent involved, eutecticetfects which may result from their combination and the melting point ofthe vehicle and intensity of melt agitation.

Vehicle modifiers Depending on the melting point of the vehicle, theproper viscosity for a fluid injectable state of the melt can ordinarilybe obtained by adjusting the temperature of the melt between about 160F. and about 300 F., preferably about 180 F. to about 250 F., the meltthinning as the temperature is increased. However, since it is usuallydesirable to use temperatures in the lower part of these ranges, it hasbeen observed that certain materials when added to the molten dispersionreduce its viscosity, thus permitting lower injection temperatures. Fromto about 8% of organic vehicle modifiers can be used. Vehicle modifierscan broadly be classed as alkylene glycols having molecular weights upto about 150 and monoand di-esters of such alkylene glycols and fattyacids containing to 18 carbon atoms, aliphatic monohydric alcoholscontaining 1 to 3 carbon atoms, esters of phthalic acid and fattyalcohols containing 5 to 18 carbon atoms, and glycerol. Specificexamples are propylene glycol, ethylene glycol, diethylene glycol,triethylene glycol, hexylene glycol, glycerol, ethanol, methanol,isopropanol, propylene glycol monocaproate, propylene glycolmonolaurate, propylene glycol dilaurate, dicaprylyl phthalate, dilaurylphthalate and the like, Propylene glycol and its lauric acid esters arepreferred.

Surface active agents, dialkyl sulfosuccinates, e.g., sodium dioctylsulfosuccinate, are eflective vehicle modifiers when used instead of orin addition to the above modifiers in amounts up to about 8%.

Ordinarily, vehicle modifiers are used in only sufficient amounts toobtain the desired viscosity at a desired temperature, since excessamounts of vehicle modifiers may tend to unduly soften the finished bar.

Closed die molding process persed in a fluid injectable state using theagitator 5 and supplying heat to the crutcher, for example, with a steamjacket or steam coils 6a. Vehicle modifiers, perfumes or other additivescan be added to the crutcher 6 from their supply 3, before, after orwhile the vehicle and synthetic detergent are delivered.

If gas is to be incorporated in the melt in the crutcher 6, for examplein order to obtain a finished bar 12 which will float in water, the gasis introduced from its source 4. The entire crutcher 6 can be under gaspressure or the gas can be injected into the melt under pressure. Gassuch as air which is occluded in dry ingredients tends to remain whenthe ingredients are melted. Occluded gas plus gas which is entrappedduring agitation of the melt in the cturcher can be enough to result ina bar which will float on water. Gas can be removed from the melt bydrawing a vacuum on the crutcher 6. This may be done to remove occludedand entrapped air so that a controlled amount of gas such as nitrogencan be later introduced in the melt under pressure. Specific gravitiesof the finished bar 12 can range from about 0.5 to about 1.1(substantially gas-free) by controlling the amount of gas in the melt. Aspecific gravity of about 0.9 is preferred for a bar which floats onWater.

When the ingredients of the melt are substantially uniformly dispersedin a fluid injectable state, the melt is circulated through theinjection circuit 9, a pipeline which contains a heat exchanger 8 usedto stabilize the temperature of the melt and which continuouslyrecirculates the melt through the crutcher 6. This continuousrecirculation supplements the action of the agitator 5 in the continuousagitation of the melt which is essential to maintain the properviscosity and uniform dispersion of the melt as hereinbefore described.If the molten dispersion is not continuously agitated, it would tend tobecome viscous and set up and the components of the melt would tend toseparate. A pump 7 maintains the circulating and injecting pressure.Pressures in the range of from about 1 to about 20 pounds per squareinch are satisfactory for injection and pressures in the range of fromabout 2 to about 10 pounds per square inch are preferred. Pressureswhich are too high cause splashing in the mold and increase the densityof the melt, making a floating bar difiicult to obtain.

When forming bars from the molten dispersion circulating in injectioncircuit 9, the stream is diverted by closing valve 21 and is injectedinto the mold 11 by simultaneously opening the injection valve 10.Injection valve 10 is shown in more detail as a part of the crosssection of the mold in FIGURE 2. The injection valve 10 is closed assoon as the mold 11 is filled and the circulation is resumed bysimultaneously opening valve 21. It has been found that molds forconventionally sized toilet bars are filled in from about 0.5 to about 5seconds, preferably about 1 to 2 seconds. The mold is cooled by coolingsystem 13.

The construction of a substantially closed mold (or die) suitable foruse in the closed die molding process of this invention is illustratedin FIGURE 2 which is an elevation view of the mold and injection valvein cross section. This type of mold is merely illustrative and suitablemolds are not limited to the one described. The mold is in two sections.When the molten dispersion is injected into the mold 11 from injectioncircuit 9 as shown in FIGURE 1, injection valve 10 is opened. Theinjection valve is opened as shown in FIGURE 2 by moving slidablestopper 20 out from injection port-valve seat 17 through the valvesection 19 of the injection circuit. When the injection valve is opened,the molten dispersion is injected into the mold cavity 14 of the barmold through injection port-valve seat 17. While the mold cavity 14 isbeing filled, the air contained therein is forced out through vent 18.This vent consists of a slit-like space between the two mold sectionsand is located at the top of the mold. Vent 18 is closed by 1 l the meltfilling the mold, being chilled and solidified at that point. The moldcavity 14 is closed by returning slidable stopper into the injectionport-valve seat 17.

The vent 18 is preferably located near the top of the mold 11 to reduceany tendency of the vent to be sealed by the injected molten dispersionbefore all air has been displaced from the mold.

The injection port-valve seat 17 can be of a variety of sizes and shapessuch as round holes or slits. Round ports about A to about V2 inch indiameter result in good injection with a minimum of bar defacement. Thesize of the injection port can be varied with the injection speed andpressure being used and with the viscosity of the molten dispersion. Ifthe size of the port is increased, more rapid injection at lowerpressures are possible. A larger sized injection port may be desirablefor use with higher viscosity molten dispersions and injection portsequiva' lent to l" or more in diameter may be used.

The shape of mold cavity 14 governs the shape of the finished bar 12 andcan be of practically any shape so long as there is no undercuttingwhich would prevent ejection of a whole bar from the mold. The mold 11is preferably split into halves to facilitate its opening and closingand the ejection of the finished bar 12. It is suflicient if the moldsections meet at the largest perimeter of the bar cavity 14. If thecavity14 is highly polished, the finished bar 12 has a very smooth shinysurface.

If will be understood that the term injection ineludes any means forintroducing the molten stock under pressure into the mold. Suitablyarranged movable mold sections and means for introducing the moltenstock, such as that shown in copending application Serial No. 830,652,may be used instead of the method herein described.

The mold 11 is precooled so that the injected molten dispersion issolidified to at least a form sustaining shell as rapidly as possible.The mold 11 is enclosed with a hollow core cooling jacket 16. Within thehollow core 15 chilled brine is circulated so that the mold 11 and themold cavity 14 are cooled. The brine is chilled and circulated in andout of the mold 11 by the refrigerating system 13. Liquids other thanbrine may be used for the coolant, e.g. fluorinated hydrocarbons such asFreon. The mold 11 can be cooled by other means; for example, the mold11 can be packed in solid carbon dioxide or the mold 11 could be offinned construction and be cooled by a blast of chilled air.

Process of solidification When the molten dispersion is injected intothe precooled, substantially closed mold, the solidification beginsalmost immediately in the outermost portion or shell of the molten barstock and proceeds toward the center of the bar. Injection is veryrapid, the mold being filled in about 0.5 to about 5 seconds, preferablyabout 1 to 2 seconds. solidification is a function of time and moldtemperature. For speed of production, a short period for holding themolten bar stock in the mold is desirable, e.g. less than about 5minutes, preferably less than about 2 minutes. To obtain such a shortperiod a low mold temperature is desirable. However, extremely low moldtemperatures increase refrigeration requirements and may tend to causethe bar to crack because of too rapid cooling. High mold temperaturesincrease the time that molten stock must be held in the mold forsolidification as well as increasing the tendency of the bar to stick tothe inner surfaces of the mold. It has been found that the mold shouldbe precooled to a temperature in the range of about F. to about F., andpreferably to a temperature in the range of about -l0 F. to about +30F., for optimum results, such as minimum tendencies for the barcompositions to stick, crack or require long holding times in the mold.The optimum mold temperature within this range varies with thecomposition of the melt, the melting point of the mix and thetemperature of the melt as it is injected into the mold.

12 temperature decreases the thermal a particular mold temperature.

Ejection of the bar from the mold takes place by opening the mold andremoving the bar or allowing it to drop out. Complete solidification isnot required before the bar can be ejected from the mold. Moreover,complete solidification within the mold is not desirable, since itunduly slows production. Cooling the molten stock to a point where thebar has a solid shell thick enough and strong enough to allow the bar toretain its shape unsupported, permits ejection of the bar from the moldfor subsequent cooling outside the mold and complete solidification eventhough the interior still may be molten. Further cooling for about 5 toabout it) minutes can be done in a cooled tunnel or room, for example.For toilet bars of the conventional size, i.e. about to 150 cc. (usuallyabout cc.), a solid shell about to about /a of an inch thick permitsejection from the mold before complete solidification and can beobtained in about i to about 2 minutes under the conditions aboveindicated. The shell, interior and surface of an injection molded barare shown in FIGURE 3.

The formation of the aforementioned rigid shell is additionallyadvantageous because it permits the bar to take a surface finish fromthe mold walls even though the bar is removed from the mold beforecomplete solidification. In a floating bar, the shell has differentphysical characteristics from the bar interior and results in certainadvantages. Study of the bar shell shows that it is about 5% to 10% moredense, and has finer crystalline structure, than the bar interior,apparently because of the more rapid initial chilling of the shell inthe mold and the subsequent slower cooling of the bar interior. Sincethe shell is more dense and has finer crystalline structure than theinterior, it acts as a firmer, smoother, less porous coating for theless dense interior. The shell protects the bar interior by reducingwater absorption, escape or perfume and mart-ing. Milled and freezerbars, by the nature of their manufacture, do not have such a protectiveshell.

It has been found that about 3 to about 6 B.t.u.s of heat must beabstracted by the cooled mold from a body of molten material forming aconventionally sized bar during a commercially feasible time for holdingthe melt in the mold in order to obtain a strong, form-retaining shell.A total of about 16 to about 25 B.t.u.s must be abstracted for completesolidification, the remaining heat being abstracted by cooling outsideof the mold. This abstracted heat includes heat of crystallization andthe sensible heat which is necessary to cool the melt to thecrystallization point.

The cooling procedure of the closed die molding process of thisinvention as applied to the uniform dispersions described herein resultin detergent bars of excellent strength smoothness, firmness anduniformity of structure.

In the closed die molding process of this invention the mold is filledrapidly before any substantial solidification, thus avoiding thetendency for orientation of structure and cleavage planes of thedetergent bars made by the milling, freezer or framing methods.Therefore, the detergent bars of this invention will not wet-crackbecause they do not have the orientation of structure and cleavageplanes formed in bars made of other processes.

Additives The normally solid anionic sulfated and sulfonated organicsynthetic detergents which are necessary ingredients in the process andcompositions of this invention have been previously described.Detergents other than these can be added, if desired, to the moltendispersion in amounts up to about 10%, without substantially detractingfrom the injectability of the molten dispersion or from thecharacteristics of the finished bar composition and in many cases may bebeneficial. These detergent Lowering of the melt cracking tendency atadditives can include anionic non-soap synthetic detergents such ashigher acyl sarcosinates, (e.g. sodium lauroyl sarcosinate), andnonionic non-soap synthetic detergents such as a high molecular weight(e.g. 8000) condensate of ethylene oxide with a polypropylene glycol(e.g. Pluronic F68) and other nonionic detergents known in the art.

Water-soluble, normally solid, higher fatty acid soaps can be includedin the bar composition in amounts up to about 15%, preferably no morethan 10%, to give the user of the finished bar an impression ofsoap-feel to which he may be accustomed, although this is entirelyunnecessary to realize the advantages of a synthetic detergent bar.Soaps are useful in some combinations of synthetic detergent and vehicleto reduce the tendency of the injected bar to crack on cooling. Thesoaps which can be used include, for example, the sodium salts of thefatty acids of natural oils and fats such as tallow and coconut oil.Soap in the melt in amounts in excess of about 15% interferes withviscosity control and proper solidification of the molded bar.

For convenience or economic reasons, it may be desirable to fill" ordilute the bar composition with a normally solid impalpable substancewhich does not adversely aflfmt the viscosity characteristics of themolten dispersion of synthetic detergent and vehicle, the injectionprocess or the characteristics of the detergent bar com.- position.Fillers can be used in the bar compositions in amounts up to about 30%,preferably not more than 20%.

Materials which can be used as tillers or diluents for detergent barsare, for the most part, commonly used and well known in the art. Thesematerials are naturally impalpable such as those of a waxy nature or arefinely ground to a size of about 75 microns or smaller. Conventionalfiller materials include: substantially insoluble, finely groundminerals such as talc, felspar, quartz, calcium carbonate, bentonite,fuller's earth, clay, kaolin; finely ground inorganic salts of low tomoderate solubility such as alkali metal, e.g. sodium, phosphates,chorides and sulfates; finely ground organic materials of low solubilitysuch as starch, calcium and magnesium soaps and polyethylene glycolswith molecular weights of 4000 to 20,000. Alkali metal, e.g. sodium,chlorides and sulfates in a fine form usually accompany anionicsynthetic detergents as by-produots from their manufacture and the incorporation of such salts in the bars of this invention is usuallyunavoidable. These salts are inert with respect to the product andprocess of this invention, particularly as shown in Examples 18, 19, 22,23 and 24. Oxidized starch, sodium sulfate, and polyethylene glycolswith molecular weights of 4000 to 20,000 are the preferred fillers.

Many other materials useful in the production of detergent bars can beadded to the molten dispersion without substantially afl eoting themolding process. These materials include minor amounts of perfumes,whiteners such as titanium dioxide, bactenostatic agents, emollients,dyes and foaming or lathering agents.

Additives can comprise up to about 43%, preferably not more than 35%, byweight of the finished detergent bar. Dispersed additives which arenormally solid appear to increase the viscosity of the melt onlyslightly. Additives which are not normally solid (including vehiclemodifiers and water) should not comprise more than about 10% by weightof the finished bar in order to avoid softening of the bar.

Water The synthetic detergent bar compositions of this invention can besubstantially anhydrous. This characteristic is advantageous in thatthere is no "drying-out of the bar in storage or use. Drying out iscommon in milled and freezer bars and promotes warping and wet cracking.%15% moisture content is usually a requirement for detergentcompositions undergoing milling operations and greater amounts arerequired for freezer operations. The ingredients of the bar compositionsof this invention can be processed dry, but ordinarily contain up toabout 1% moisture. Up to about 5% water can be tolerated in the moltendispersion to be injected. Amounts of water greater than about 5% tendto increase the viscosity of the melt, cause undesirable steam andfoaming in the melt, and soften the finished bar.

EXAMPLES The following examples are given to illustrate the manner inwhich this invention can be practiced. Its scope is not limited by theingredients named in the examples since it is apparent that some can beinterchanged with each other or equivalents substituted. Likewise, itsscope is not limited to the proportions shown in the examples since theproportions can be varied to adjust for variations in properties ofsubstituted equivalent ingredients. All parts are by weight.

Example I.The following ingredients were added to a crutcher, heated toabout F. and agitated for about 20 minutes until the synthetic detergentwas dispersed in the fatty alcohol vehicle:

55 parts sodium alkyl glyceryl ether sulfonate, the alkyl radical beingproduced from a fractionated fatty alcohol mixture derived from thereduction of coconut oil and consisting of about 2% decyl alcohol, 66%lauryl alcohol, 23% myristyl alcohol and 9% cetyl alcohol.

37 parts stearyl alcohol.

5 parts of a mixture of sodium chloride and sodium sulfate asby-products of the detergent salt manufacture.

2 parts propylene glycol.

1 part perfume.

Nitrogen gas was dispersed and emulsified in the melt by introducing itat about 10 pounds per square inch pressure. The melt was run into theinjection system and circulated by pump at about 5 pounds per squareinch pressure. A portion of the melt was rapidly injected into the moldwhich was cooled with refrigerated brine to about 0" F. The dispersionwas held in the mold for about 2.5 minutes after which the bar had astrong solid shell about Vs" thick. The bar was then ejected from themold even though its interior was still warm and soft. After furthercooling the bar was observed to be firm, strong and smooth surfaced. Itlathered well in hard or soft water. In wasbstand use the bar cleansedwell and formed none of the hardwater curd and scum common to soap. Uponcontinued use, no wet-cracking tendency characteristic of milled, framedor freezer" detergent bars was observed.

The melt was kept continuously circulating and as soon as a finishedcooled bar was ejected from the mold, the mold was closed and anotherportion of the melt was injected into the mold in a manner similar tothe first injection with substantially equal results. This process wasrepeated until the volume of the melt became too small to circulate. Abattery of molds can be filled by injection simultaneously to increasethe number of detergent bars produced in a given time.

Example II.-The following ingredients were added to a crutcher, heatedto about F. and agitated for about 20 minutes:

45 parts sodium alkyl glyceryl ether sulfonate described in Example I.

3 parts sodium alkyl benzene sulfonate, the alkyl group being derivedfrom polypropylene and averaging about 12 carbons.

7 parts sodium N-methyl-N-coconut oil fatty acid taurate.

25 parts hydrogenated tallow fatty acid containing about 65 35 stearicacid, 33% palmitic acid and 2% myristic 2 parts propylene glycol.

9 parts oxidized corn starch.

1 part water.

1 part perfume.

7 parts a mixture of sodium sulfate, sodium chloride which accompany thedetergent salts as by-products of manufacture.

The molten dispersion resulting was run into the injection system andcirculated by pump at about 8 pounds per square inch pressure. Occludedand entrapped air was emulsified and dispersed in the melt. A portion ofthe melt was rapidly injected into a mold, which was cooled withrefrigerated brine to about F. The dispersion was held in the mold forabout 3 minutes and the bar was ejected. After further cooling, the barwas firm, strong and smooth surfaced. It floated in water, lathered andcleansed well, was mild to the skin, formed no washstand curd and wasnon-cracking.

Example IIL-A detergent bar was closed die molded using the followingmaterials in accordance with the procedure described in Example IIexcept for the changes in conditions listed below:

40 parts sodium N-methyl-N-coconut oil fatty acid taurate.

23 parts hydrogenated tallow fatty acid described in Example H.

parts oxidized cornstarch.

7 parts propylene glycol.

1 part water.

1 part perfume.

18 parts sodium chloride as a by-product of manufacture of the detergentsalt.

The mold was cooled to about 30 F.; the injection temperature was about180 F.; the injection pressure was about 5 pounds per square inch; theinjection time was approximately one second; nitrogen gas wasincorporated in the melt; the molten stock was held in the mold forabout one minute and the bar with a solidified shell was then ejected.After further cooling the resulting bar was an excellent, floating,strong, non-cracking, mild, rich lathering, toilet bar.

Methanol, ethanol and ethylene glycol can be substituted for thepropylene glycol in Example III with substantially equal results both ininjection molding and bar performance.

Example I V.-A bar with properties similar to those described in Example11 and closed die molded in accordance with the procedure described inthat example (except for the changes in conditions listed below) wasmade of the following ingredients:

45 parts sodium alkyl glyceryl ether sulfonate described in Example I.

30 parts hydrogenated tallow fatty acids described in Example II.

2 parts propylene glycol.

1 part perfume.

7.3 parts oxidized cornstarch.

4.7 parts of a mixture of sodium sulfate and sodium chloride (by-productof detergent production).

4 parts sodium alkyl benzene sulfonate described in Example II.

6 parts sodium salt of sulfated coconut oil fatty alcohol containingabout 66% lauryl alcohol, 23% myristyl alcohol, 9% cetyl alcohol and 2%decyl alcohol.

An injection temperature of about 180 F., an injection pressure of about8 pounds per square inch, a mold tem- 16 perature of about -8 F. and acooling time of about 2 minutes were used.

Example V.-A bar with properties similar to those described in ExampleII and closed die molded in accordance with the procedure described inthat example (except for the changes in conditions listed below) wasmade of the following ingredients:

30 parts sodium-N-methyl-N-coconut fatty acid taurate.

10 parts coconut oil fatty acid ester of sodium isethionate.

25 parts hydrogenated tallow fatty acid described in Example II.

7 parts propylene glycol.

1 part perfume.

17 parts sodium chloride as a by-product of manufacture of the detergentsalts.

10 parts oxidized cornstarch.

An injection temperature of about 230 F. and an injection time of about0.5 seconds, a mold temperature of about 30 F. and a cooling time ofabout 3 minutes were used.

Example VI.The following ingredients were added to a crutcher, heated toabout 220 F. and agitated until they were dispersed in the fatty acidvehicle:

42 parts coconut oil fatty acid ester of sodium isethionate.

12 parts stearic acid.

12 parts palmitic acid.

5 parts sodium salt of sulfated coconut oil fatty alcohol.

4 parts dioctyl ester of sodium sulfosuccinate.

5 parts sodium coco-nut oil alcohol sulfoacetate.

7 parts sodium coconut oil soap.

4 parts propylene glycol.

0.4 part titanium dioxide.

0.8 part perfume.

6.8 parts of a mixture of sodium chloride and sodium sulfate as aby-product of manufacture of the detergent salts.

1 part moisture.

After the resulting molten dispersion was deaerated by drawing a vacuumon the system, nitrogen gas was dispersed therein. The melt was then runinto the injection circuit and circulated by pump at about 5 pounds persquare inch pressure. A portion of the melt was rapidly injected intothe mold which was cooled with refrigerated brine to about 20 F. Thedispersion was held in the mold for about one minute which was longenough for a strong, solid, shape-sustaining shell to form. The bar wasejected from the mold and further cooled for about 7 minutes in acooling tunnel without deformation. Sufficient nitrogen gas had beenintroduced in the molten dispersion so that the resulting bar had anoverall density of about 0.9 and floated in water. The bar was firm,strong and smooth surfaced; it lathered excellently. It exhibited no wetcracking tendencies. When the bar was cut in half, a shell about Vs inchthick having a density of about 0.97 was observed.

In Example VI, propylene glycol monolaurate, propylene glycol dilaurate,propylene glycol dioleate, ethylene glycol monolaurate, ethylene glycoldimyristate, triethylene glycol, hexylene glycol, glycerol and dilaurylphthalate can be substituted for the propylene glycol with substantiallyequal results in both closed die molding and the performance of thefinished bar.

The following table of bar composition examples will serve to illustratewide variety of formulations which can be closed die molded according tothe process of this invention. All parts are by weight. The formulationsinclude about 1% moisture.

Examnl 7 8 9 10 11 12 13 14 15 16 17 18 Detergent:

Sofilum alkylbenzene (described in Example Sodium alkyl glyceryl ethersulfonate (den n on scribed in Example 55 55 55 55 55 55 55 51.9 51.951.9 55 32.9

Coconut oil fatty acid ester oi sodium isethionate SOdlilm sult ofsulfated coconut oil fatty alco- Dioctyl ester of sodium sulfosuccinateSodium salt of sulfated coconut oil monoglyeerlde Potassium alkylsulfonate derived from a mixture of straight chain a olefins Vehicle:

Myristic Acid Palmitic Acid.-. Stearic Aeid Arachidic Acid Bchenic AcidMyristyl Alcohol Cetyl Alcohol. Stearyl Alcohol"- Arachidyl AlcoholBehenyl Alcohol Glycerol Monostearatc Diethylene Glycol Distearate.Ethylene Glycol Monostcarato Glycerol Dipalmitate Additives:

Propylene Glycol 2 2 2 Perfume 1 Polyethylene glycol (mol, wt. 20,000)Polyethylene glycol (mol. Wt. 4,000). Oxidized corn starch Coconut oilsoap s:

Example 19 20 21 22 23 24 25 26 27 28 29 Detergent:

Sodium alkylbenzene (described in Example II) 5 5 Sodium alkyl glycerylother sulfonate (described in Example I) Coconut oil fatty acid ester ofsodium isethionate. Sodium salt ofsulfated coconut oil fatty alcoholDioctyl ester of sodium sullosuccinate Sodium salt of sulfated coconutoil monog1yeeride- Potassium alkyl sulfonate derived from a mixture ofstraight chain a olefins Vehicle:

My'ristic Acid Palmitic Acid Stearic Aeid Arachidic Aci Behenic AcidMyristyl Alco Cetyl AleohoL Araellidyl Alco Behenyl Alcohol. GlycerolMonoste Diethylcne Glycol Distcara Ethylene Glycol Monostearat GlycerolDipulmitatm Additives:

Perfume Polyethylene gl Polyethylene glycol (1110] Oxidized corn starchMixture of sodium ch] Coconut oil soap The detergent bars of thisinvention have outstanding utility as toilet bars, e.g. personalwashstand and bath use. However, they are also useful as shaving soapsor for the hand washing of wool and fine fabrics, for example.

Various modifications and variations of this invention will be obviousto persons skilled in the art and it is to be understood that suchmodifications and variations are to be included within the purview ofthis application and the spirit and scope of the claims.

What is claimed is:

1. In the process of closed die molding a detergent bar, the steps of(1) forming, for injection, :1 fluid melt comprising a mixture of fromabout 35% to about 70% normally-solid, water-soluble, anionic, non-soap,synthetic detergent and from about 22% to about 50% normallysolid fattyvehicle having a melting point between about F. and 220 F. selected fromthe group consisting of saturated higher molecular weight fatty acidsand alchols and monoand di-cstcrs of said fatty acids and a polyhydricalcohol selected from the group consisting of glycerol, ethylene glycoland dicthylenc glycol, by heating said mixture to a temperature in therange of from about F. to about 300 F. and with agitation substantiallyuniformly dispersing said detergent in said vehicle, the temperature andproportions of said detergent and vehicle being such that the resultingmolten dispersion has a viscosity in the range of from about 2000 toabout 50,000 centipoises at the conditions of injection and such thatsaid dispersion will cool through the nigre plus crystals phase, (2)continuously agitating said dispersion prior to injection, (3) injectingsaid dispersion into a substantially closed bar mold, filling said mold,said mold being prccooled to a temperature in the range of about 30 F.to about +40 F. and suflicient to form rapidly at least a solid,shape-sustaining shell for said bar, (4) ejecting said bar from saidmold.

2. The process of claim 1 with the additional steps of incorporating gasin the fluid melt sufficient to obtain a detergent bar capable offloating in water and subjecting the ejected bar to further cooling forcomplete solidification.

3. The process of claim 2 wherein the carbon chains in said vehiclerange in length from about 16 to about 22, the ratio of syntheticdetergent to vehicle is in the range of about 2.5:1 to about 1.2: 1, themixture of synthetic detergent and vehicle is heated to a temperature inthe range of about 180 F. to about 250 F. and the substantially closedmold is precooled to a temperature in the range of from about 10 F. toabout +30 F.

4. The process of claim 3 in which up to about 8% of a vehicle modifierselected from the group consisting of alkylene glycols having molecularweights up to about 150, esters of said alkylene glycols and fatty acidscontaining to 18 carbon atoms, aliphatic monohydric alcohols containing1 to 3 carbon atoms, glycerol, and esters of phthalic acid and fattyalcohols containing 5 to 18 carbon atoms, is added to the moltendispersion in step (1) to reduce viscosity.

5. The process of claim 3 in which the detergent is selected from thegroup of alkyl glyceryl ether sulfonates, acyl isethionates and N-methylacyl taurides in which at least 50% of the alkyl and acyl groupsrespectively contain 12 carbon atoms in a straight saturated chain andthe vehicle consists of fatty acids ranging in chain length from 16 to18 carbon atoms.

6. In the process of closed die molding a detergent bar, the steps of(1) forming, for injection a fluid melt comprising a mixture of fromabout 40% to about 60% normally-solid, water-soluble, anionic, non-soap,synthetic detergent and from about 24% to about 35% normally-solid fattyvehicle having a melting point between about 130 F. and about 190 F.selected from the group consisting of saturated higher molecular weightfatty acids and alcohols and monoand di-esters of said fatty acids and apolyhydric alcohol selected from the group consisting of glycerol,ethylene glycol and diethylene glycol, the carbon chains in said vehicleranging from about 16 to about 22, by heating said mixture to atemperature in the range of from about 180 F. to about 250 F. and withagitation substantially uniformly dispersing said detergent in saidvehicle, the temperature and proportions of said detergent and vehiclebeing such that the resulting molten dispersion has a viscosity in therange of from about 2000 to about 50,000 centipoises at the conditionsof injection and such that said dispersion will cool through the nigreplus crystals phase, (2) continuously agitating said dispersion prior toinjection, (3) injecting said dispersion into a substantially closed barmold, filling said mold, said mold being precooled to a temperature inthe range of about F. to about +30 F. and suflicient to form rapidly asolid, shape-sustaining shell for said bar, (4) ejecting said bar fromsaid mold, (5) subjecting said bar to further cooling for completesolidification.

7. The process of claim 6 with the additional step of incorporating gasin the fluid melt sufiicient to obtain a detergent bar capable offloating in water.

8. The process of claim 7 in which up to about 8% of a vehicle modifierselected from the group consisting of alkylene glycols having molecularweights up to about 150, esters of said alkylene glycols and fatty acidscontaining 5 to 18 carton atoms, aliphatic monohydric alcoholscontaining 1 to 3 carbon atoms, glycerol, and esters of phthalic acidand fatty alcohols containing 5 to 18 carbon atoms, is added to themolten dispersion in step (1) to reduce viscosity.

9. The process of claim 7 in which the detergent is selected from thegroup consisting of alkyl glyceryl ether sulfonates, acyl isethionatesand N-methyl acyl taurides in which at least 50% of the alkyl and acylradicals respectively contain 12 carbon atoms in a straight saturatedchain and the vehicle consists of fatty acids ranging in chain lengthfrom 16 to 18 carbon atoms.

10. In the process of closed die molding a detergent bar, the steps of(1) forming, for injection, a fluid melt consisting essentially of amixture of from about 40% to about 60% normally-solid, water-soluble,anionic, nonsoap, synthetic detergent from about 24% to about 35%normally solid fatty vehicle having a melting point between about F. and190 F. selected from the group consisting of saturated higher molecularweight fatty acids and alcohols and monoand di-esters of said fattyacids and a polyhydric alcohol selected from the group consisting ofglycerol, ethylene glycol and diethylene glycol, the carbon chains insaid vehicle ranging from about 16 to about 22 carbon atoms, 0% to about10% soap, 0% to about 30% normally solid impalpable filler material, and0% to about 8% propylene glycol to reduce the viscosity of the melt, byheating said mixture to a temperature in the range of from about F. toabout 250 F. and with agitation substantially uniformly dispersing insaid vehicle said detergent, soap, filler and propylene glycol, thetemperature and proportions of said ingredients being such that theresulting molten dispersion has a viscosity in the range of from about2000 to about 50,000 centipoises at the conditions of injection and suchthat said dispersion will cool through the nigre plus crystals phase,(2) continuously agitating and circulating said dispersion prior toinjection, (3) injecting said dispersion into a substantially closed barmold, filling said mold, said mold being precooled to a temperature inthe range of about 10 F. to about +30 F. and sufficient to form rapidlya solid, shape sustaining shell for said bar, (4) ejecting said bar fromsaid mold, (5) subjecting said bar to further cooling for completesolidification.

11. The process of claim 10 with the additional step of incorporatinggas in the fluid melt sufficient to obtain a detergent bar capable offloating in water.

12. The process of claim 11 in which the detergent is selected from thegroup consisting of alkyl glyceryl ether sulfonates, acyl isethionatesand N-methyl acyl taurides in which at least 50 of the alkyl and acylradicals respectively contain 12 carbon atoms in a straight saturatedchain and the vehicle consists of fatty acids ranging in chain lengthfrom about 16 to 18 carbon atoms.

13. In the process of closed die molding a floating detergent bar, thesteps of (1) forming, for injection, a fluid melt consisting essentiallyof a substantially anhydrous mixture of from about 40% to about 60% of adetergent selected from the group consisting of alkyl glyceryl ethersulfonates, acyl isethionate and N-methyl acyl taurides in which atleast 50% of the alkyl and acyl radicals respectively contain 12 carbonatoms in a straight saturated chain, from about 24% to about 35% ofsaturated fatty acids ranging in chain length from about 16 to 18 carbonatoms, 0% to about 10% soap, 0% to about 30% normally solid impalpablefiller material and 0% to about 8% of a lauric acid ester of propyleneglycol to reduce the viscosity of the melt, by heating said mixture to atemperature in the range of from about 180 F. to about 250 F. and withagitation substantially uniformly dispersing in said vehicle saiddetergent, soap, filler and ester, the temperature and proportions ofsaid ingredients being such that the resulting molten dispersion has aviscosity in the range of from about 2000 to about 50,000 centipoises atthe conditions of injection and such that said dispersion will coolthrough the nigre plus crystals phase, (2) incorporating gas in thefluid melt suflicient to obtain a detergent bar capable of floating inwater, (3) continuously agitating and circulating said dispersion priorto injection, (4) injecting said dispersion into a substantially closedbar mold, filling said mold, said mold being precooled to a temperaturein the range of about -10 F. to about +30 F. and suflicient to formrapidly a solid, shape sustaining shell for said bar, (5) ejecting saidbar from said mold,

(6) subjecting said bar to further cooling for complete solidification.

14. A closed-die molded detergent bar having a protective shell which isdenser than the interior of the bar, said bar being free from thecleavage planes and orientation of structure characteristic of milleddetergent bars and said bar comprising from about to about normallysolid, Water soluble, anionic, non-soap synthetic detergentsubstantially uniformly dispersed in from about 22% to about 50%normally-solid fatty vehicle having a melting point between about F. and220 F. selected from the group consisting of saturated higher molecularweight fatty acids and alcohols and monoand di-esters of said fattyacids and a polyhydric alcohol selected from the group consisting ofglycerol, ethylene glycol and diethylene glycol, said bar havingsufficient gas dispersed therein so as to be capable of floating inwater.

15. A closed die molded detergent bar having a protective shell which isdenser than the interior of the bar, said bar being free from cleavageplanes and orientation of structure characteristic of milled detergentbars and said bar comprising from about 40% to about 60% normally solid,water soluble, anionic, non-soap synthetic detergent substantiallyuniformly dispersed in from about 24% to about 35% normally solid fattyvehicle having a melting point between about F. and about F. selectedfrom the group consisting of saturated higher molecular weight fattyacids and alcohols and monoand di-esters of said fatty acids and apolyhydric alcohol selected from the group consisting of glycerol,ethylene glycol and diethylene glycol, the carbon chains in said vehicleranging from about 16 to about 22 in length, said bar having sufiicientgas dispersed therein so as to be capable of floating in water.

16. The detergent bar of claim 15 wherein the said detergent is selectedfrom the group consisting of alkyl glyceryl ether sulfonates, acylisethionates and N-methyl acyl taurides in which at least 50% of thealkyl and acyl radicals respectively contain 12 carbon atoms in astraight saturated chain and the vehicle consists of fatty acids rangingin chain length from 16 to 18 carbon atoms, said bar containingadditionally 0% to about 10% soap and 0% to about 30% normally solidimpalpable filler material.

References Cited in the file of this patent UNITED STATES PATENTS838,127 Markel Dec. 11, 1906 1,244,297 Curland Oct. 23, 1917 2,329,288Miller Sept. 14, 1943 2,359,013 Tucker Sept. 26, 1944 2,478,013 RoddyAug. 2, 1949 2,535,436 Maynard Dec. 26, 1950 2,803,043 Stephens Aug. 20,1957 2,871,516 Sherman et a1. Feb. 3, 1959 UNITED STATES PATENT OFFICECERTIFICATE OF CORRECTION Patent No. 2 987 484 June 6, 1961 Olle I.Lundberg et a1.

It is hereby certified that error appears in the above numbered patentrequiring correction and that the said Letters Patent should read ascorrected below.

' column Column 7 line 44, for "7%" read 70% 12, line 64, for "of" readby column 19, line 64,

for "carton" read carbon Signed and sealed this 21st day of November1961.

(SEAL) Attest:

ERNEST W. SWIDER DAVID L. LADD Commissioner of Patents Attesting OfficerUSCOM M-DC

1. IN THE PROCESS OF CLOSED DIE MOLDING A DETERGENT BAR, THE STEPS OF (1) FORMING, FOR INJECTION, A FLUID MELT COMPRISING A MIXTURE OF FROM ABOUT 35% TO ABOUT 70% NORMALLY-SOLID, WATER-SOLUBLE, ANIONIC, NON-SOAP, SYNTHETIC DETERGENT AND FROM ABOUT 22% TO ABOUT 50% NORMALLYSOLID FATTY VEHICLE HAVING A MELTING POINT BETWEEN ABOUT 120*F. AND 220*F. SELECTED FROM THE GROUP CONSISTING OF SATURATED HIGHER MOLECULAR WEIGHT POINT BETWEEN ABOUT CHOLS AND MONO- AND DI-ESTERS OF SAID FATTY ACIDS AND A POLYHDRIC ALCOHOL SELECTED FROM THE GROUP CONSISTING OF GLYCEROL, ETHYLENE GLYCOL AND DIETHYLENE GLYCOL, BY HEATING SAID MIXTURE TO A TEMPERATURE IN THE RANGE OF FROM ABOUT 160*F. TO ABOUT 300*F. AND WITH AGITATION SUBSTANTIALLY UNIFORMLY DISPERSING SAID DETERGENT IN SAID VEHICLE, THE TEMPERATURE AND PROPORTIONS OF SAID DETERGENT AND VEHICLE BEING SUCH THAT THE RESULTING MOLTEN DISPERSION HAS A VISCOSITY IN THE RANGE OF FROM ABOUT 2000 TO ABOUT 50,000 CENTIPOISES AT THE CONDITIONS OF INJECTION AND SUCH THAT SAID DISPERSION WILL COOL THROUGH THE NIGRE PLUS CRYSTALS PHASE, (2) CONTINUOUSLY AGITATING SAID DISPERSION PRIOR TO INJECTION, (3) INJECTING SAID DISPERSION INTO A SUBSTANTIALLY CLOSED BAR MOLD, FILLING SAID MOLD, SAID MOLD BEING PRECOOLED TO A TEMPERATURE IN THE RANGE OF ABOUT -30*F. TO ABOUT +40*F. AND SUFFICIENT TO FORM RAPIDLY AT LEAST A SOLID, SHAPE-SUSTAINING SHELL FOR SAID BAR, (4) EJECTING SAID BAR FROM SAID MOLD. 